1. Field of the Invention
This invention relates to ceramic-metal laminates, and more particularly, to the method for making a laminate of this type which enables thermal strains to be taken up without harmful effects and to the article produced by the method.
2. Description of Prior Art
A number of methods are known in the prior art for joining a metal member to a ceramic section. For example, U.S. Pat. No. 2,996,401 shows a method for use in electron tube manufacture where the surface of the ceramic body is metallized with refractory metals and the metal member is then brazed to the metallized coating. Another example, U.S. Pat. No. 3,114,612, shows a ceramic laminate useful for high temperature applications where the ceramic is coated with a metallic bonding medium and welded to a corrugated stainless steel sheet.
While these prior art methods are satisfactory in uses for which they were designed, in high temperature operation under oxidizing conditions and mechanical stress, such as encountered in gas turbine engines, the required laminates must have the ability to withstand the substantial strains due, in part, to extreme differences in amounts of thermal expansion which are created during turbine's operation and in part due to the thermal gradients across them. The prior art items tend to be anisotropic in their ability to absorb thermal strains and there is a need for an attachment method that will respond to thermal strains elastically at moderately low stress levels in all directions.